Investigations of heat transfer characteristics in channels with supercritical fluids are crucial for power cycle applications, such as supercritical water-cooled reactors. To ensure the safety of the system, heat transfer deterioration (HTD) should be avoided. The criteria to identify the onset of HTD in heated rod bundles are still not determined. This study summarizes indicators for the onset of HTD in a rod bundle with supercritical water flowing upward based on observations from experimental data. Existing criteria for the tube flow are assessed by comparing predicted critical heat flux (CHF) values with experimentally identified values. Considering effects of different operating parameters, a new criterion for predicting HTD behavior in rod bundles is developed. The results indicate that the new criterion has a better performance than all existing criteria, with a mean average relative deviation of 0.26 %. Predicted CHF values are within ± 20 % of the respective experimentally identified CHF values.

中文翻译：

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开发超临界水向上流动预测棒束临界热通量的新准则

研究超临界流体通道中的传热特性对于超临界水冷反应堆等动力循环应用至关重要。为了确保系统的安全，应避免传热恶化（HTD）。识别加热棒束中 HTD 发生的标准尚未确定。本研究根据实验数据的观察总结了超临界水向上流动的棒束中 HTD 开始的指标。通过将预测的临界热通量 (CHF) 值与实验确定的值进行比较来评估现有的管流标准。考虑到不同操作参数的影响，开发了一种预测棒束中 HTD 行为的新标准。结果表明，新准则比所有现有准则具有更好的性能，平均相对偏差为 0.26%。预测的 CHF 值在各自实验确定的 CHF 值的 ± 20% 范围内。